When birds mingrate into or out of a defined population and mate with birds from another population. The existing pool of genes may be altered migration can increase or decrease gene frequencies in population.. A: greater genetic variation which may enhance chances of survival
B: less genetic variation which will not influence chances of survival
C; selective breeding which may enhance chances of survival
D: natural selection which will not influence chances of survival

Liquid ammonia is produced at high temperatures and under great pressure in a tank by passing a mixture of nitrogen gas and hydrogen gas over an iron catalyst. the reaction is represented by the following equation. n2(g) + 3h2(g) → 2nh3(g) changing all but one experimental condition will affect the amount of ammonia produced. that condition is a) increasing the concentration of both reactants b) changing the temperature within the tank c) decreasing the pressure within the tank. d) increasing only the amount of nitrogen present.